Add resource image list and virtual location

Bundled a couple current requests, and so far have only changed the ttl file. Will need to update the UML and generated pyLOAD once this is reasonably clear. Probably won't add examples, may update a little text on the location side.

The image list is an additional property, the image property remains. People could either or both or neither.

The resource virtual location I think doesn't need to be changed by an economic event like the resource physical location is, but this does not preclude that if the requirement arises.